Bye Bye duplicate content, Canonical URLs to the rescue!
Well it’s not strictly true, duplicate content will still be an issue for a lot of sites!
Anyway, last week at SMX West, Google, Yahoo and MSN announced that they now accept the rel=”canonical” variable.
What does this mean?
Let’s take a look at Majestic Wine. Their site uses a large database which displays wines based on your choices from the navigation on the left hand side.
Majestic Wines Canonical URLs - Example 1
In the above example I’ve selected Wine > France > Loire > White
This URL was generated:
http://www.majestic.co.uk/find/category-is-Wine/category-is-France/category-is-Loire/Colour-is-White+Wine
However if I then select them in a different order, i.e. Wine > White > France > Loire, I get this URL:
http://www.majestic.co.uk/find/category-is-Wine/Colour-is-White+Wine/category-is-France/category-is-Loire
Despite the 2 different URLs the page content is exactly the same. Until now search engines may have seen this as duplicate content but now that they’ve introduced rel=”canonical”, this will no longer be a problem for ecommerce sites.
So how do Canonical URL Links work?
It’s similar to a 301 redirect but only works on internal pages, don’t try to use this for external domains, it won’t work.
Decide which page you want to be indexed and regarded as “the one”, then with all of the other “lesser” duplicate pages add to the <head> section:
<link rel=”canonical” href=”http://www.example.com/product.php?item=the_one” />
In the case of Majestic Wine they may employ something like this;
<link rel=”canonical” href=”http://www.majestic.co.uk/find/category-is-Wine/category-is-France/category-is-Loire/Colour-is-White+Wine” />
This will now ensure that if another variation is selected it will redirect to the preferred page and it will pass on Page Rank and all links from that page.
Simples!
For more details check out: http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html
